Ambulance staff across the north-east and Highlands are being asked to send a vote of no confidence to management.
Ballot papers have been issued to Unite members, amid claims that serious concerns raised by staff to their bosses are being ignored.
Union organisers have dismissed media statements from management about problems being addressed as “spin”.
Earlier this month, a man died in Elgin four days after being hit by a lorry on the A96 near Dr Gray’s Hospital.
It later emerged the region had two ambulances transferring patients to Aberdeen at the time and only the “chance” of an ambulance arriving at the accident and emergency department with a patient prevented Gerard Campbell from being killed at the scene.
Issues such as vehicles being made unavailable for 999 calls due to ferrying patients to non-essential appointments, Aberdeen services being “propped up” by rural crews and the absence of proper rest breaks are among a list of concerns raised with bosses.
Paramedics have spoken out in the Press and Journal in recent months about the intolerable pressure they are working under and failings they are witnessing.
Tommy Campbell, Unite regional officer for Aberdeen, said: “It’s very disappointing we have to go down this route, but we’ve spent nearly a year raising concerns with senior management – and it doesn’t seem to be getting anywhere.
“This is not a pay issue. This is about serious concerns from staff who feel they are unable to deliver this valuable service to the public.
“They are concerned about themselves, the stress of the situation they find themselves in, but it is all being caused by the same thing.”
The ballot follows alarming revelations that Elgin paramedics were “rationing” oxygen, following an office blunder and pleas from staff for more cover just months before teenager Keiran McKandie was killed after being hit by a car while cycling.
Ambulance staff have been given the option of saying they have “lost confidence” in management or whether they still have faith.
A vote against bosses would trigger a formal dispute resolution procedure between the union and management.
An ambulance service spokesman added: “We are aware of the letter to Unite members in our North Division.
“With regards to the concerns over the provision of the ambulance service, we are continuing to work with staff-side colleagues to address the issues raised.”
The result of the ballot is expected next month.